1. Field of the Invention
The present invention relates to a computer program product, system, and method for migrating high activity volumes in a mirror copy relationship to lower activity volume groups.
2. Description of the Related Art
Disaster recovery systems typically address two types of failures, a sudden catastrophic failure at a single point in time or data loss over a period of time. In the second type of gradual disaster, updates to volumes may be lost. To assist in recovery of data updates, a copy of data may be provided at a remote location. Such dual or shadow copies are typically made as the application system is writing new data to a primary storage device. Different copy technologies may be used for maintaining remote copies of data at a secondary site, such as International Business Machine Corporation's (“IBM”) Extended Remote Copy (XRC), Coupled XRC (CXRC), Global Copy, and Global Mirror Copy. In data mirroring systems, data is maintained in volume pairs. A volume pair is comprised of a volume in a primary storage device and a corresponding volume in a secondary storage device that includes an identical copy of the data maintained in the primary volume. Primary and secondary control units, also known as storage controllers or enterprise storage servers, may be used to control access to the primary and secondary storage devices. In peer-to-peer remote copy operations (PPRC), multiple primary control units may have source/target pairs, i.e., volume pairs, included in consistency groups so that data copied to target volumes by the different primary control units maintains data consistency.
When establishing a mirror copy relationship, the administrator may set up copy relationship between volumes in a session that may be grouped according to Logical Subsystem (LSS), where there may be multiple LSSs, each grouping multiple volumes, and where the LSSs are assigned to one session. Data consistency may be maintained among the mirror copy operations between the volumes in the LSSs assigned to a session.
In current mirror copy arrangements where multiple volumes in volume groups are being mirrored to a remote storage site location, certain volumes or LSSs may experience relatively high levels of I/O activity and updates which can cause delays that lead to suspensions and performance degradation. If the administrator notices that the workload is not properly balanced among the LSSs, then the administrator may move volumes among sessions and LSSs to balance the workload.